An electronic instrument needs to be connected to whatever circuit, device, or system that is being tested. This is typically accomplished by a probe that is connected, by the user, to the circuit under test. This probe establishes an electrical connection with the circuit node under test, and passes the signal present at that node down a cable to the instrument.
Unfortunately, the non-ideal properties of real world cables can cause the signal to be degraded as it passes down the cable from the probe to the instrument. This signal loss increases with frequency. The loss of these high-frequency components causes signals, such as square-waves, to appear inaccurately when displayed on an oscilloscope. In particular, a square-wave will appear to have a rounded leading edge when displayed on an oscilloscope.
Accordingly, there is a need in the art for an apparatus and method that compensates for the loss of high-frequency signal components due to the non-ideal properties of real world cables. It is desirable that the solution minimize the size of the probe tip, both for the convenience of the user, and to minimize the capacitive loading of the probe on the circuit under test. Furthermore, many users find it desirable to be able to change the attenuation of the signal entering the instrument as well as the probe impedance. The solution should accommodate that desire.